code: def test_join_non_unique(self):
      left = Index([4, 4, 3, 3])
  
      joined, lidx, ridx = left.join(left, return_indexers=True)
  
      exp_joined = Index([4, 4, 4, 4, 3, 3, 3, 3])
      tm.assert_index_equal(joined, exp_joined)
  
      exp_lidx = np.array([0, 0, 1, 1, 2, 2, 3, 3], dtype=np.intp)
      tm.assert_numpy_array_equal(lidx, exp_lidx)
  
      exp_ridx = np.array([0, 1, 0, 1, 2, 3, 2, 3], dtype=np.intp)
      tm.assert_numpy_array_equal(ridx, exp_ridx)
  
file_path: pandas/pandas/tests/indexes/numeric/test_join.py
imports: import numpy
  import pytest
  import pandas._testing
  from pandas.core.indexes.api import Index
label_desc: Use image node_id 1 for calling the TestJoinInt64Index obj's underlying member method code with example usage: obj.test_join_non_unique() without return types